Mattress



FIG. 1 is a left side, top perspective view of a mattress showing my design in its intended environment;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side view thereof, the right side being a mirror image thereof;

FIG. 4 is a foot end view thereof, the head end being a mirror image thereof; and,

FIG. 5 is a bottom plan view thereof.

The broken lines shown in the drawings are included for the purpose of illustrating environmental structure and form no part of the claimed design. 

CLAIM I claim the ornamental design for a mattress, as shown and described. 